Transmission links (e.g., cables) are employed in a variety of communication systems. For example, transmission links are often used in communication systems including, but not limited to, telecommunication systems, security systems, sound systems, television broadcasting systems, internet broadcasting systems, power distribution networks, and so forth. Transmission links can age, and as a result, their link quality can deteriorate over time. In some cases, aged transmission links may not be identified and replaced until they are no longer useful (e.g., no longer capable of transmitting coherent data signals). Methods of objectively assessing link quality of transmission links are needed to detect aged transmission links before they cause interruptions within the communication systems in which they are deployed.